ABSTRACT
People incur costs to achieve goals. Costs consist of responses and time; physical and psychological energy; and opportunity costs, which are the activities a person rejected in order to work on achieving a goal. Effort as a cost subtracts from goal value through effort discounting. Like money, motivation resources consist of reflex reserve (bank of responses), learned industriousness, and grit along with available time and energy. Demand Law: Incentive demand goes up when its cost goes down; incentive demand goes down when its cost goes up. Fatigue means being tired and not functioning effectively. Fatigue indicates that current costs are high and benefits are low compared to those of an alternative. This comparison motivates a shift to an alternative activity. People are governed by least effort: They are motivated to achieve high-level goals with minimum expenditure of effort.
